Ever consider going to a counselor by yourself or with him?

Trust issues aren't easily fixed. However, just because you feel compelled to do something doesn't mean that you have to do it. For example, just because you feel the need to check his email doesn't mean that you have to actually check it. Trust is built over time and you're not going to learn to trust him if you constantly expect him to lie to you.

You don't have to believe every thought that pops into your head. Thoughts lie all the time. If you want a healthy relationship, you have to learn to be strong enough to be vulnerable even if it is unpleasant for a while. The only way to protect yourself against cheating/lying/getting hurt is to not date and to live in a cave somewhere. Acting controlling towards the guy is just going to make you both miserable.

And I seriously suggest counseling.